A strong built-in electric field(V_(bi))is the key to achieving rapid separation of photogenerated carriers in perovskite solar cells.This is particularly important for hole transport layer(HTL)free carbon-based perov...A strong built-in electric field(V_(bi))is the key to achieving rapid separation of photogenerated carriers in perovskite solar cells.This is particularly important for hole transport layer(HTL)free carbon-based perovskite solar cells(C-PSCs),which have a large interface energy level mismatch.The regulation of perovslite's surface energetics is an effective way to improve the V_(bi)and promote charge extraction,which is typically achieved by organic molecules.However,the insulating nature of organic molecules also negatively hinders charge transfer,resulting in a contradiction of"extraction-transport".Quantum dots(Q.Ds)have great potential for energetics regulation of perovskite film due to their semiconductor properties and inherent large dipole moments,but have not yet been explored.In this work,we propose a strategy of discrete embedding semiconductor QDs at the surface grain boundaries of the perovskite film to regulate surface energetics.The QDs change the energetics of the perovskite film surface,transforming the surface energetics from n-to p-type,thus constructing p-n homojunction at the interface.This significantly enhances the Vbi at the perovskite/carbon electrode interface,promoting hole extraction.In addition,the embedded discrete distribution of QDs at the upper surface grain boundaries ensures efficient transport of the extracted holes to the carbon electrode,overcoming the contradiction of"extraction-transport"for traditional energetics control strategies.Consequently,the fabricated planar HTL-free C-PSCs achieve an efficiency of 20.10%(certified 19.8%),which is one of the highest values reported for this kind of device.展开更多
基金supported by the National Natural Science Foundation of China(NFSC No.22122805,U21A20310,22075090,and 22278164)the Science and Technology Program of Guangzhou,China(No.2024A04J1540)。
文摘A strong built-in electric field(V_(bi))is the key to achieving rapid separation of photogenerated carriers in perovskite solar cells.This is particularly important for hole transport layer(HTL)free carbon-based perovskite solar cells(C-PSCs),which have a large interface energy level mismatch.The regulation of perovslite's surface energetics is an effective way to improve the V_(bi)and promote charge extraction,which is typically achieved by organic molecules.However,the insulating nature of organic molecules also negatively hinders charge transfer,resulting in a contradiction of"extraction-transport".Quantum dots(Q.Ds)have great potential for energetics regulation of perovskite film due to their semiconductor properties and inherent large dipole moments,but have not yet been explored.In this work,we propose a strategy of discrete embedding semiconductor QDs at the surface grain boundaries of the perovskite film to regulate surface energetics.The QDs change the energetics of the perovskite film surface,transforming the surface energetics from n-to p-type,thus constructing p-n homojunction at the interface.This significantly enhances the Vbi at the perovskite/carbon electrode interface,promoting hole extraction.In addition,the embedded discrete distribution of QDs at the upper surface grain boundaries ensures efficient transport of the extracted holes to the carbon electrode,overcoming the contradiction of"extraction-transport"for traditional energetics control strategies.Consequently,the fabricated planar HTL-free C-PSCs achieve an efficiency of 20.10%(certified 19.8%),which is one of the highest values reported for this kind of device.
